I can't imagine so many American fans traveling to the UK to support any fighter.

American promoters don't do a good enough job promoting fighters in their home town/city before they move them to the big venues. What I mean by that is, if they prove to be very good championship level fighters they move them to one of the big fight venues in Vegas or New York too quickly. They end up in the Barclays centre, or one of the casino's in Vegas because of the money they are able to put up, whereas they would be better off building the fan base first taking a financial hit in the short term, so that once they do hit Vegas or New York they will be taking a built in fans base with them. In this way they will actually sell more tickets easier, and the gates will do better, rather than putting up fights in Vegas which are half empty with zero atmosphere.

This is the way UK promoters do it, obviously Ricky Hatton is an extreme example. The UK geographically isn't so big, word gets around faster, this creates a buzz and the fan base tends to grow a little quicker. But there is no reason why US fighters couldn't do better if they followed a similar system. I think Bob Arum has started to understand this, and for example, with Crawford he keeps taking him back to Omaha every couple of fights, and that is what I am talking about. Not every fighter is going to come from a part of the country where this strategy works, but in general I think the fighters, especially the real talented one's need to stay and build themselves in their home town first, or the nearest large city or town to them, so they can get a local following.